I just resolved a similar issue for myself. Newly added subfields in groups weren’t appearing, nor were newly added subfields in layouts in flexible content fields. Using the “Generate PHP” feature in the tools panel fixed it for me. It may be worth a shot for you.
Welcome to the Advanced Custom Fields community forum.
Browse through ideas, snippets of code, questions and answers between fellow ACF users
2022 was a big year for Advanced Custom Fields, with more capabilities, a new generation of ACF Blocks, a refreshed UI, and a new home. Our year in review post looks at advancements we’ve made and offers a glimpse of the future. https://t.co/HahJUCcyH4